1. Field of the Invention
The present invention relates to an optical magnetic field sensor, particularly an optical magnetic field sensor which can measure a magnetic field strength with high precision using Faraday's effect.
2. Related Art Statement
Heretofore, various structures of the optical magnetic field sensor have been known which uses Faraday's effect for measuring a magnetic field strength. As an example, JP-A-61-82,179 discloses a method of measuring a magnetic field strength capable of making the measurement with high precision wherein a light beam intensity ratio of two (P and S) polarized light beams passed through a Faraday element and emitted from an analyzer is used to correct errors resulting from light beam losses at the light beam transmission paths which are not relative to the Faraday's effect. P type polarization being defined as a light beam component which has a polarization direction parallel to a surface defined by an incident light beam which is incident to a polarizer or an analyzer and an emitted light beam emitted from the polarizer or the analyzer. S type polarization is defined by light beam component that has a polarization direction vertical to the above described surface.
In the technique of the above JP-A-61-82,179, a light beam intensity ratio (where a=J.sub.1 /J.sub.2) of a P polarized light beam intensity J.sub.1 to a S polarized light beam intensity J.sub.2 emitted from an analyzer is preliminarily determined at the time when a magnetic field is not applied on the optical magnetic field sensor, and a treatment of regularization of signals at the time of receiving the signals when a magnetic field is applied on the optical magnetic field sensor is performed wherein the S polarized light beam intensity J.sub.2 is multiplied by the above ratio a, so that the errors resulting from light beam losses at the light transmission paths can be corrected. However, the technique of JP-A-61-82,179 performs merely the treatment of regularization of signals of multiplicating J.sub.2 by the above ratio a, so that signal errors resulting from temperature could not be corrected and a problem arose in that it can not be used as a highly precise optical magnetic field sensor suitable for use at large temperature change.